Electrical problem. Relay, maybe?

[vbrad511]

Hey all, hoping this is the right place to post this. I've got a '97 4wd, 4.0, 5 speed. Off and on for a few years now, occasionally when I get in the truck there's no dome light, and when I turn the key, no dash lights, no crank. Sometimes the dash lights are on very dimly. Sometimes I hear what sounds like a relay clicking, but cycling the key a few times, and everything returns to normal. Is there some main relay under the dash? That's all I can think of at this point. I've replaced the battery, the connections are all clean, even added an extra ground to the block. Suggestions, anybody?

 

[Curious Hound]

Sounds like the ignition switch may be worn or loose so that the key isn't actuation it completely all the time.

Also, there is a 50 or 60 amp fuse in the engine bay that sends power to the ignition switch so that it can power the interior fuse panel. But a fuse will usually be good or bad, not intermittent, unless you have an unusual amount of corrosion in the fuse panel.

 

[vbrad511]

Sounds like the ignition switch may be worn or loose so that the key isn't actuation it completely all the time.

Also, there is a 50 or 60 amp fuse in the engine bay that sends power to the ignition switch so that it can power the interior fuse panel. But a fuse will usually be good or bad, not intermittent, unless you have an unusual amount of corrosion in the fuse panel.

I thought that too, but that wouldn't affect the dome light when I open the door, would it?

 

[2011Supercab]

Battery cables can also corrode under the insulation.

 

[RonD]

Yes, battery cable ends and battery terminals, clean them FIRST

There is no 12volts without 0Volts(battery negative), so BOTH need to be clean and tight

The "clicking" relay means low voltage in the vehicle, so its a symptom not a cause, same as the dim lights are a symptom of low voltage

 

[vbrad511]

Yes, battery cable ends and battery terminals, clean them FIRST

There is no 12volts without 0Volts(battery negative), so BOTH need to be clean and tight

The "clicking" relay means low voltage in the vehicle, so its a symptom not a cause, same as the dim lights are a symptom of low voltage

I've done this. This is also not the only battery in the truck since it began, and i've changed the terminals too. Also pulled the positive cable and feed wires from the solenoid and cleaned them all up. Is there somewhere else I should be looking?

 

[RonD]

Not really
The dome light has power all the time, activated by GEM module when door is opened

The dash/cluster is ignition switch on power

There is no connection between them except battery/engine bay fuse box

On the starter relay there is the smaller red wire from battery positive
Then the smaller red wire to engine fuse box
ALL vehicle electrical power comes thru those 2 wires, with engine off

With engine on, Alternator's voltage output is on that same starter relay post(Grey fusible link wire) and it powers ALL the vehicle electrics thru the smaller red wire to engine fuse box, and charges the battery thru the other smaller red wire to battery positive

The only other thing they have in common is the Cabs Ground wire, its on the back of drivers side head and attaches to the firewall, either with its own bolt or on the wiper motor's mounting bolt
This ground strap is often left off after engine work
The cab/body sits on rubber mounts and is bolted to the frame with little or no metal to metal contact, so Cab needs a good ground


1996/7 electrics are the same

 

[vbrad511]

Not really
The dome light has power all the time, activated by GEM module when door is opened

The dash/cluster is ignition switch on power

There is no connection between them except battery/engine bay fuse box

On the starter relay there is the smaller red wire from battery positive
Then the smaller red wire to engine fuse box
ALL vehicle electrical power comes thru those 2 wires, with engine off

With engine on, Alternator's voltage output is on that same starter relay post(Grey fusible link wire) and it powers ALL the vehicle electrics thru the smaller red wire to engine fuse box, and charges the battery thru the other smaller red wire to battery positive

The only other thing they have in common is the Cabs Ground wire, its on the back of drivers side head and attaches to the firewall, either with its own bolt or on the wiper motor's mounting bolt
This ground strap is often left off after engine work
The cab/body sits on rubber mounts and is bolted to the frame with little or no metal to metal contact, so it need a good ground


1996/7 electrics are the same

Something I haven't checked is that body ground strap. I'll have a look at it tomorrow. Thank you.

 

[vbrad511]

Not really
The dome light has power all the time, activated by GEM module when door is opened

The dash/cluster is ignition switch on power

There is no connection between them except battery/engine bay fuse box

On the starter relay there is the smaller red wire from battery positive
Then the smaller red wire to engine fuse box
ALL vehicle electrical power comes thru those 2 wires, with engine off

With engine on, Alternator's voltage output is on that same starter relay post(Grey fusible link wire) and it powers ALL the vehicle electrics thru the smaller red wire to engine fuse box, and charges the battery thru the other smaller red wire to battery positive

The only other thing they have in common is the Cabs Ground wire, its on the back of drivers side head and attaches to the firewall, either with its own bolt or on the wiper motor's mounting bolt
This ground strap is often left off after engine work
The cab/body sits on rubber mounts and is bolted to the frame with little or no metal to metal contact, so Cab needs a good ground


1996/7 electrics are the same

Didn't make a difference. I cleaned the forward and the firewall straps, bolts, studs, wire ends with 220 sandpaper. I got back in the truck after I got it together, dead....for a few cycles of the key before everything "woke up". I do have headlights when the interior and dash is dead.

 

[RonD]

Then its probably inside the engine fuse box, you need to look at power distribution that dome light and ignition switch have in common

 

[vbrad511]

Just to update....turned out the battery terminals I put on were...kinda flimsy. I swapped them out for a set that's a bit beefier and it's been fine for a few weeks now.
Thanks for the help everybody